The present invention relates to an adjustable casing for a helical spring, and more particularly to an adjustable casing including two cases and a rotation member for enclosing a helical spring therein, so that the helical spring therein could be adjusted to different modulus of elasticity to meet requirements of equipment onto which the helical spring is mounted.
A conventional helical spring has a modulus of elasticity that is decided when the helical spring is manufactured. Since there are various kinds of machines that require different magnitudes of stretching or compressing force, helical springs of different specifications are manufactured for use on different machines. For a helical spring of a given specification and unit deformation, the lower the number of active coils of the helical spring is, the higher the modulus of elasticity is, and the larger a stretching or compressing force is needed to deform the helical spring, and the higher the number of active coils of the helical spring is, the lower the modulus of elasticity is, and the lower a stretching or compressing force is needed to deform the helical spring. Since a conventional helical spring has a specification that is designed according to the machine on which the helical spring is mounted, and the modulus of elasticity of the helical spring is not freely adjustable, the conventional helical spring has limited flexibility in its usage.
It is therefore tried by the inventor to develop an adjustable casing for helical spring to enable free adjustment of the modulus of elasticity of a helical spring mounted in the casing.
A primary object of the present invention is to provide an adjustable casing for helical spring, so that a helical spring mounted in the adjustable casing could be freely adjusted to a desired modulus of elasticity depending on actual needs of a machine to which the helical spring is mounted.
A technical principle employed by the present invention is that the modulus of elasticity of the helical spring could be changed through change of the number of active coils subjected to a compressing force or a stretching force. With the present invention, a helical spring is able to bear different stretching or compressing force while the unit deformation of the helical spring remains unchanged.
To achieve the above and other objects, the adjustable casing for helical spring of the present invention mainly includes a male and a female case, and a rotation member. A helical spring is enclosed in the casing with an end fixedly connected to a fixing seat provided at a bottom center of the female case and another end located in the male case. The rotation member is provided around an outer or an inner surface with a plurality of stoppers that are adapted to engage with coils of the helical spring. When the rotation member is rotated, the number of active coils of the spring subjected to a compressing or a stretching force is changed, and the modulus of elasticity of the helical spring is adjusted, accordingly.